A text input method from among character input methods in conventional terminals, which will hereinafter be referred to as a ‘T9’ method, outputs frequently used characters by combinations of key inputs. The T9 method predicts a character to be input by a user in order to solve inconvenience in conventional character input methods. Using the T9 method, the user can output a desired character by pressing a key corresponding to the character once, as will be described with reference to FIG. 1 which illustrates a key input unit in a conventional terminal.
When the user desires to input ‘pizza’ in the key input unit illustrated in FIG. 1, numeric keys corresponding to characters have to be pressed in order of 7, 4, 4, 4, 9, 9, 9, 9, 9, 9, 9, 9, 2. In other words, the user has to press a key corresponding to a desired character several times in order to input the desired character. For example, in order to input ‘z’, the user can select ‘z’ from among four characters ‘wxyz’ assigned to a key 101 by pressing the key 101 four times. Moreover, when a character assigned to a key has to be input several times, the user may feel confused.
However, according to the T9 method, the desired word ‘pizza’ can be output by pressing once a key 104 to which ‘p’ is assigned, pressing one a key 103 to which ‘i’ is assigned, pressing twice a key 101 to which ‘z’ is assigned, and pressing once a key 102 to which ‘a’ is assigned. In other words, according to the T9 method, if the user presses numeric keys ‘7’, ‘4’, ‘9’, ‘9’, 2′ including characters ‘p’, ‘i’, ‘z’, ‘z’, ‘a’, respectively, a terminal can output a word ‘pizza’ predicted by searching a previously stored dictionary. Thus, the user can conveniently input desired characters with a smaller number of key inputs when using the T9 method than when using conventional character input methods.
However, according to the T9 method, a problem occurs when the user desires to input a proper noun. According to the T9 method, only words predicted based on user's key inputs can be input. As a result, the user has to switch an input mode in order to select a desired character. Namely, the user can input a desired character only after switching an input mode from a T9 mode to a separate input mode. To this end, the user has to additionally input a mode switch key. In particular, the has to press the mode switch key several times when inputting a sentence composed of several words, increasing the overall number of key presses. This is also because the structure of characters displayed in the key input unit does not change even if the user presses the mode switch key. In other words, since two or more characters are assigned to each key even after switching to the separate input mode, an increase in the number of key inputs for character selection is inevitable.
As such, in a conventional terminal, the user has to perform a separate operation for mode switch in order to input a desired character, e.g., for a proper noun, in the T9 mode. Consequently, the user has to select a mode for character input whenever necessary, making more efforts for key input. Moreover, in order to input characters one by one, several key inputs are required to output a corresponding character, making a character input process complex and increasing the time required for the character input process.
As such, according to the prior art, the user has to switch an input mode in a separate way in order to input a proper noun in the mode using the T9 method. The conventional character input method requires an operation for mode switch for each character input, the character input process is complex and the time required therefor increases. Moreover, the conventional key input unit has a structural problem in that several key inputs are still required for character selection even after switching to the separate input mode.